Lethal Effect of High Electric Fields on Microorganisms

Abstract

The lethal effect of high electric fields on Escherichia coli K-12 IAM-1264 and on spore of Bacillus subtilis IAM-1169 has been studied.
Electric field strength was more weak than spark discharge, and added to suspension of the organisms by the series of direct current pulses.
The lethal effect was influenced by the electric field strength, the capacity, the number of discharges and the viscosity of the solution. The spore of Bacillus subtilis was more difficult to inactivate than Escherichia coli. From this experiment, the equation for inactivation of microorganisms was obtained:
dn/dt=-k'ndε/dt
where n is the number of microorganisms in unit volume, and ε, the electric energy added to the test solution per unit volume at time t. If it is assumed that the total electric energy is converted to kinetic energy of ions in aqueous medium, the inactivation equation is:
n=n₀e-k1/2 αE²C/η²
where n₀ is the initial viable number of microorganisms in unit volume t=0 sec; E, electric field strength V/cm; C, electric capacity; α, addition number of electric pulse; η, viscosity of the solution and k, the constant.